Tension device for sewing-machines



(No Model.)

S. P. BROWN. TENSION DEVICE FORSEWING MACHINES.

No. 319,448. Patented June 9, 1885.

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SAMUEL P, BROWN, on nnrnenronr, CONNECTICUT.

TENSION DEVICE FORlSEWiNG NiACHlNES.

SPECIFIGATION forming part of Letters Patent 1\ T0. 319, M8, dated June 9, 1885.

Application filed September 22, 1884. (No model.)

To all whom, it may concern.-

Be it known that I, SAMUEL I. BROWN, a citizen of the United States,residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Tension Devices for Sewing-Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention is applicable to all classes of machines in which either the upper or lower threads, or both, are carried by a spool or bobbin having an opening through its center, and has for its object to provide a tension which shall be easy to adj ust, and when adj ust-ed shall be substantially uniform whether the spool or bobbin be full of thread or nearly empty.

Heretofore sewing-machine tensions have been gotten by friction upon the thread-as, for example, by the pressure of a spring or by threading in and out of holes-or else by friction of spring or washers against the spool or bobbin, or against a disk around which the thread passes. All of these styles of tensions, however, have proved far from satisfactory in their operation, as it has been impossible to so adjust the tension devices as to produce an even strain upon the thread when the bobbin was full and when nearly empty, and to make them work uniformly on different styles of thread.

For the purpose of remedying the above objections I have devised the simple and novel justing-screw; Fig. 3, aperspective ofthecase,

showing the carrier and the spring, the bobbin being removed; Fig. 4, a perspective of the bobbin; Fig. 5, a central section showing my invention applied as an upper-thread tension and Fig. 6, across-section, as in Fig. 5, showing the spline made sharp to engage and hold the spool.

l Similar letters indicate like parts in all the figures.

A is the spool or bobbin case for an under tension, and B a stud or standard projecting outward therefrom. This stud or standard is internally screw-threaded to accommodate the adjusting-screw O.

D is a spring loosely coiled around the stud at either end. I

E is the spool or bobbin carrier, which is free to rotate on the stud, and is provided with a key or spline, E, for a purpose presently to be explained.

F is the spool or bobbin, which may be of any desired shape. F is the central opening through this spool or bobbin, and Fa groove at one side of the central opening corresponding with the key or spline E, which I make in the spool or bobbin when made of metal.

G represents washers of rawhide, hard rubber, or any suitable material, which I preferably place 011 opposite sides of the carrierthat is, next to the spring and the head of the screw. In assembling the parts washers are placed on opposite sides of the carrier, the spring being placed on either side of the carrier, as may be thought best. The adjustingscrew is then turned in to hold the parts in place. The washers and screw-head are preferably made of slightly less diameter than the carrier, so that the spool or bobbin will slip on and off the standard freely. It will thus be seen that the spool or bobbin can only rotate with the carrier, owing to the engagement of the spline and groove.

In Figs. 5 and 6, in which my invention is applied as an upper-thread tension, I have shown the key or spline upon the carrier made sharp, so that when a spool is forced down upon it the key or spline will cut into the wood of the spool, so as to hold it firmly, and cause it to rotate with the carrier. The action of the spring as the adj usting-screw is tightened up will be to press one washer against the car rier and the latter against the other washer. The two washers are thus made to press against the ends of the carrier with more or less power, according as the adjusting-screw is tightened or loosened.

It will be seen that when used as an under tension no threading up is required, except the passage of the thread through the case;

that the-bobbin maybe removed andreplaced withoutin any waylaffecting the tension, and that the tension maybe changed without removing the boblpin or the thread.

I have illustrated my improved under tension inconnection with the bobbin and bob; bin-case of a Wheeler & Wilson machine; but it will of course be understood that my invention is equally applicable to other kinds of machines, thesole requirement being that the spool or bobbin have a central opening.

The general shape of the bobbin orthe bobbin-case is not of the essence of my present in; vention. For example, a wooden or other spool may be used instead of a metallic bobbin; orthebobbi'n-case may be dispensed witlr,

and the bobbincarrier, spring, and screw applied in connection with a rotary or oscillating shuttle having a stud. As stated above,my invention relates to the tension alone, and is applicable to theupp'er or under thread of any machine in which the spool or bobbin has an opening through its center, the essential feature being that the spool or bobbin is keyed tothe' carrier, to

bin of a carrier keyed thereto, a stud upon which the carrier is adapted to rotate, a spring and washers upon said stud, and a screw engaging therewith,whereby the friction of the Washers upon the carrier may be regulated.

2. The bobbin-case having a central stud upon which the carrier is adapted to rotate, in combination with the bobbin keyed to the carrier, a-spring acting on the carrier, and a screw engaging the stud, which acts to adjust the tension byfor'cing the carriefagainst the spring as it is turned in'.

In, testimony whereof I affix my signature in presence of two witnesses.

SAMUEL r. BROWN.

Witnesses:

A. M. Woosrnn, WM. A. J ONES. 

